In her best-selling book “Longitude” Dava Sobel outlines how two different approaches were employed to address an 18th century transportation problem — the need for ships at sea to be able to determine their location.

Leading solutions included a complex, time-consuming method that involved (no kidding) observing the positions of the moons of Jupiter. A simpler method employed clocks to compare local time with that in the ship’s home port. The problem was while this method was easier, the construction of clocks that would run accurately at sea made the option much more daunting.

Today, the automotive industry faces a similar problem of improving the efficiency of our cars, and again we see two primary solutions vying to address our problem — diesel engines and hybrid gas-electric drivetrains.

The 2008 Toyota Highlander Hybrid falls into the latter camp. It pursues the immediately useful — if costly and complex — solution of using electric motors and batteries to supplement a gasoline-powered, V-6 powerplant to save on fuel. Sea clocks — chronometers — were eventually the preferred solution for maritime navigation, but neither hybrids nor diesels are likely to beat the other in the automotive marketplace of the future. Instead, they will coexist and eventually even combine forces.

For those customers who need a roomy, seven-seat family vehicle that uses as little gas as possible, the Highlander Hybrid is the sole available option. But as good as it is, thrifty-minded drivers may be disappointed to discover that they can only expect to see 23 or 24 mpg in real-world, around-town driving (the EPA ratings are 27 mpg city and 25 mpg highway).

Sierra Clubbers who thought they were buying moral superiority with their hybrid may also be shocked to discover that the Highlander is no Prius. (Perhaps Toyota will soon offer a four-cylinder hybrid in the seven-seat RAV4 as a thriftier option.)

While the Highlander’s efficiency is only OK in absolute terms, it’s pretty good for a three-row, all-wheel-drive vehicle that hauls around a family of five in comfort during cold winter weather. By way of comparison, a GMC Acadia I tested last winter managed only half the Highlander’s around-town fuel economy in the same driving conditions.

In its recent models Toyota has raised the condition of “Toyota-ness” to a new high.

Toyota

For those who need a roomy, fuel-sipping seven-seat family vehicle the Highlander Hybrid SUV is the sole available option.

The bland, blocky exterior styling of the Highlander suits the hard antiseptic interior plastics and numb, uncommunicative electric power steering to yield what could be the perfectly soulless transportation appliance, ready for sale at your nearest big box discount store and designed to dissolve into invisibility in your suburban neighborhood.

Still, credit is due for Toyota’s ability to give the hard plastic cabin materials a matte finish, suggesting maybe the Highlander is ready for Target’s shelves rather than Wal-Mart’s, although that sea of Rubbermaid looks ready for a disinfecting blast of Lysol next time the plague is going around the kiddies’ school.

Drivers shopping for fuel-saving family haulers probably have little expectation of driving excitement, and the hybrid version of the Highlander manages to dash even those modest hopes.

Its steering wheel feels like it might be connected to the Grand Tourismo game the kids are playing on their Playstation rather than to actual, functional front wheels.

But the steering is not the Highlander’s worst attribute. That (dis)honor goes to the brakes, which possess the ability to make every driver exhibit the finesse of a drunken driver’s ed student. Yes, you too can inadvertently race up behind a stopped car and have to slam on the brakes at the last second to avoid a collision. Snapping passengers’ heads forward in commuting traffic is child’s play, as once again you misjudge the amount of pedal pressure needed.

The problem isn’t the brakes themselves — the Highlander stops fine. It’s the calibration of a system that uses the vehicle’s electric motor as a generator to recharge its battery during deceleration. It’s supposed to maximize fuel efficiency, but in its current form it’s just too intrusive.

A driver can also help save gas by pressing the “ECON” button on the Highlander’s console. It runs a sophisticated program that modulates throttle input while lighting indicators on the dashboard that coach the driver on how much gas to apply for maximum gas mileage.

The answer for how much gas to apply is, of course, “less,” and the result of the throttle modulation is the feeling that the throttle cable has been replaced by a rubber band.

This might seem intrusive too, but in a hybrid vehicle with a continuously variable transmission, there is already so little correlation between pedal position, engine sound and vehicle acceleration that disconnecting them further in the name of better mileage seems like a good idea.

The Highlander Hybrid has another button on its console — the “EV.” It lets the driver switch the car to “electric vehicle” mode (and presumably creep silently around the neighborhood on electric-only power).

EV is a preview of plug-in hybrid technology to come, but a less-than-satisfying experience when using the “EV” mode is the reason why we don’t yet have plug-in hybrids.

The gas engine has to be warmed up and the battery almost full before you can even try to use it. That’s because if you were to hum out of your driveway on electron power with an ice-cold gas engine, and then suddenly floor it to make a traffic light in your neighborhood your call to the engine room for Warp 6 would be met by a Scottish-tinged reply: “I dannae ken if she can take any more, Captain!”

But when the conditions are just right, the EV mode engages and you can boldly go where few have gone before, but you have to accelerate oh so lightly (no faster than 25 mph) or the Highlander’s gas engine engages. And if you go more than a very short distance, the battery runs down.

Still, the Highlander has its strengths. As a crossover SUV family hauler, it keeps its first and second-row occupants comfortable and happy with multi-adjustable seats. Kids will probably tolerate the third-row seats, which are flat on the floor, but adults will wonder when the sushi will be served.

And Toyota deserves kudos for building the only fuel-saving, three-row family wagon available. The Highlander hybrid is a good first step, but what we really need is a practical vehicle that gets genuinely great mileage.

Customers are ready for truly economical family vehicles, and they won’t care whether engineers had to build a better clock or consult Jupiter’s moons to achieve it.